Synaptic Transmission

• 1. The action potential reaches the end of the pre synaptic neuron
• 2. At the end of the axon of the neuron , there are several sacs known as synaptic vesicles. These contain the chemical messengers that assist in the transfer of the impulse - the neurotransmitters
• 3. The vesicles move to the end of the pre synaptic neuron and release the neurotransmitter into the synapse
• 4. The released neurotransmitter diffuses across the gap between the pre and post synaptic neurons , from a high concentration to a low concentration
• 5. The neurotransmitter binds to specialised receptors on the surface of the post synaptic neuron that recognise it. This activates the receptors. An action potential starts in the post synaptic neuron
• 6. The effects are terminated at most synapses by a process called ' reuptake ' ( reabsorption). This is where the neurotransmitter is taken up again by the presynaptic neuron , to be stored for future use OR broken down
• Inhibition - the post synaptic neuron is LESS likely to fire
• Excitation - the post synaptic neuron is MORE likely to fire